Washington and Beijing must strive to build trust through “consistent and mature communications” to avoid a military mishap amid tensions in the South China Sea and Taiwan Strait, a former senior US diplomat for Asia has warned.

“We must be extra careful not to have a mishap like EP-3 in the current environment,” Susan Thornton, the former acting assistant secretary of state for East Asian and Pacific affairs, told the South China Morning Post in an interview.

“I'm not confident that we have adequate communication mechanisms in place to prevent escalation.”

Thornton, who retired from the State Department in July, was referring to the 2001 collision of a US Navy EP-3E Aries II spy plane, on a routine surveillance mission, with a Chinese PLA Navy J-8 interceptor fighter jet over the South China Sea near the Chinese coast.

A bitter diplomatic crisis arose over the incident, which left a Chinese pilot missing; his body was never found and he was declared dead. Though heavily damaged, the American plane managed to make an unauthorised emergency landing at Lingshui Air Base – a PLA Navy facility on Hainan Island.

Thornton – attempting to raise awareness of the dangers of inadequate US communication with China – said the Trump administration “should be communicating more about things we know the other side doesn't like, because there are a long list of differences on both sides”.

But she also said China needs to be “honest and more transparent” about its intentions to deploy weapons at its outposts in the South China Sea to prevent a military incident from occurring.

“If China doesn't make some kind of effort to be more forthcoming about what it's doing, what its plans are, how these islands will not be used to threaten its neighbours, and how these islands will not be used to keep the US from having access to this region, it’s just going to continue to be a festering problem,” the former top East Asian diplomat said.

She urged the countries to establish “communications and rules of behaviour mechanisms that could serve to diminish the possibility of a mishap, which is the immediate problem we face in the South China Sea”.

Thornton’s warning comes ahead of an expected meeting in Washington next week between US and Chinese defence ministers who will attempt to address their respective nations’ differences as a war of words between Washington and Beijing ratchets up over issues in the South China Sea and across the Taiwan Strait.

While it claims sovereignty over the South China Sea, China is in talks with surrounding countries over a code of conduct for the disputed maritime region.

It has long been opposed to US military aircraft and warships sailing near or overflying the disputed islands.

In late September, US and Chinese warships nearly collided when an American destroyer, the Decatur, sailed near an islet claimed by Beijing in the Spratly archipelago, known in Chinese as the Nansha Islands.

The Chinese ship came within 41 metres (135 feet) of the US vessel, leading the Pentagon to accuse the PLA Navy of conducting an aggressively “unsafe and unprofessional manoeuvre”.

Soon afterward, US Vice-President Mike Pence accused Beijing of “reckless harassment” of the US Navy and vowed America’s naval forces would “continue to fly, sail and operate wherever international law allows and our national interests demand”.

“We will not be intimidated,” he said. “We will not stand down.”

Pence also claimed that China was “militarising the South China Sea by deploying advanced anti-ship and anti-aircraft missiles atop an archipelago of military bases constructed on artificial islands”.

On Taiwan, Pence was equally critical, accusing the Chinese Communist Party in a speech last month of destabilising relations across the Taiwan Strait by convincing three Latin American nations – Panama, Dominican Republic and El Salvador – to sever ties with Taipei and recognise Beijing.

“These actions threaten the stability of the Taiwan Strait – and the United States of America condemns these actions,” Pence said.

While the US has taken a hard line with China, Beijing has recently issued some of its strongest messages ever on the South China Sea and Taiwan.

On October 25, during an inspection tour of Guangdong province, Chinese President Xi Jinping told the military region responsible for monitoring Taiwan and the South China Sea to “prepare for war”.

On the same day, Defence Minister Wei Fenghe vowed that the mainland would not cede “a single inch” of territory in the Taiwan dispute.

Thornton said the two countries could help manage the cross-Strait tensions by notifying each other in advance about planned Taiwan-related moves.

“There should be communication across the strait – what is going to happen; how and when it is going to be done,” she said. “Giving people a heads-up is generally a stabilising thing.”

The US could build trust with China by notifying it about its warships’ transit through the Strait, Thornton said. She even suggested Washington could consider telling Beijing about its planned arms sales to Taiwan, to improve relations.

Beijing regards Taiwan as a wayward province to be brought into line by force, if necessary. Although Washington switched its sovereign recognition from Taipei to Beijing in 1979, it maintains informal relations with Taiwan, providing the island with security guarantees and arms sales to support its ability to defend itself.

A reported plan by the Taiwanese coastguard to conduct “routine” live-fire drills from November 21-23 around Taiping Island, another disputed part of the Spratly archipelago, could further complicate matters. Taiping Island, known internationally as Itu Aba, is administrated by Taiwan and also claimed by mainland China, the Philippines and Vietnam.

After the PLA Air Force, including bombers and fighters, conducted military drills around Taiwan in the first half of the year, US missile-guided warships sailed through the Taiwan Strait twice in July and October in a show of support for the self-ruled island.

Further fuelling the discord, US President Donald Trump has approved two separate arms sales to Taiwan in less than 18 months. Under a 1982 pact between Washington and Taipei, the US does not consult Beijing before making decisions related to its Taiwan arms sales.